/Engine/Plugins/Media/MediaIOFramework/Source/MediaIOCore/Public/MediaCapture.h
Get the RGB to YUV Conversion Matrix, should be overriden for media outputs that support different color gamuts (ie. BT 2020). Will default to returning the RGBToYUV Rec709 matrix.
virtual const FMatrix & GetRGBToYUVConversionMatrix() const